1. Field of the Invention
The present invention relates to an apparatus for hemodialysis treatment, which performs hemodialysis and ultrafiltration by extracorporeally circulating blood of a patient.
2. Discussion of the Background
A conventional apparatus for hemodialysis treatment includes a blood circuit, a dialyzer, a blood pump and a dialysis device. The blood circuit circulates blood of a patient extracorporeally, and is connected to the dialyzer. The dialysis device performs hemodialysis and ultrafiltration by having dialysate flow into and out from the dialyzer. The blood circuit has an arterial blood circuit provided with an arterial needle at an end thereof, and a venous blood circuit provided with a venous needle at an end thereof.
When the arterial needle and the venous needle are inserted to the patient, and the blood pump is turned on, blood of the patient flows through the arterial needle into the arterial blood circuit, the dialyzer and the venous blood circuit in sequence, and then flows back into the body of the patient through the venous needle. The dialyzer includes hollow fibers forming membranes for hemodialysis. The blood flows inside of the hollow fibers. The dialysate, which has a predetermined concentration and is supplied from the dialysis device, flows outside the hollow fibers (i.e., between outside surfaces of the hollow fibers and an inside surface of a case of the dialyzer). Waste products in the blood flowing in the inside of the hollow fibers permeate into the dialysate through the membranes.
The blood flows back to the body of the patient after flowing through the venous blood circuit and after the waste products being removed from the blood. Also, the dialysis device is provided with an ultrafiltration pump that removes water from the blood. The blood is also ultrafiltrated through the membranes during the hemodialysis treatment. A volume of water to be ultrafiltrated by the ultrafiltration pump (i.e., an ultrafiltration rate) is adjusted by controlling a driving rate of the ultrafiltration pump.
When an ultrafiltration volume (i.e., a volume of water to be ultrafiltrated) is large, it is necessary to increase the ultrafiltration rate. Consequently, the patient may show shock symptoms, such as a low blood pressure, depending on health conditions of the patient. Accordingly, the conventional apparatus monitors a sign of the shock symptoms during the hemodialysis treatment by detecting a hematocrit value of the blood of the patient (i.e., a ratio of a volume of red blood cells to a volume of whole blood), and by calculating a circulating blood volume variation rate (herein “ΔBV”) of the patient based on the hematocrit value, so as to predict the sign of such shock symptoms.
In this regard, although the ΔBV of the patient normally decreases due to the ultrafiltration in a time-course of the hemodialysis treatment, a sudden decrease in the ΔBV is considered to indicate the sign of the shock symptoms. Thus, it is possible to prevent an actual showing of the shock symptoms by performing a proper preventive treatment to the patient (e.g., additionally supplying saline and suspending the hemodialysis treatment) at the time the sudden decrease in the ΔBV occurs. The above described apparatus for hemodialysis treatment is described in the Japanese Patent Application Publication No. 2004-97781.
However, sudden changes in the ΔBV may also occur due to external events such as changes in the ultrafiltration rate and hemodialysis conditions, in body positions of the patient from lying down to sitting up on the bed, and in taking food and medications. In the above-described conventional apparatus, it is difficult to compare the ΔBV with vital signs of the patient (e.g., bio-information of the patient during the hemodialysis treatment, such as a blood pressure and a pulse) that indicate the occurrence of the external events. Therefore, it is difficult to effectively relate the sudden changes in ΔBV to the sign of the shock symptoms.
In this regard, a conventional apparatus having a display is available to independently display each of the ΔBV and the vital signs in a respective screen, one screen at a time on the display, thereby having a medical staff switch between multiple screens to monitor the ΔBV and the vital signs. Also, other conventional apparatuses are available, each dedicated to detect and display either the vital signs or the ΔBV. Accordingly, a medical staff compares changes of the ΔBV and the vital signs displayed on multiple apparatuses to identify a cause of the sudden changes of the ΔBV when occurred. Consequently, when the above-described apparatus or apparatuses are used, because a medical staff is required to watch multiple screens independently by switching from one to another, or to shift the eyes between multiple apparatuses, the medical staff cannot efficiently and effectively monitor the ΔBV and the vital signs, thereby making difficult to determine whether the sudden changes in the ΔBV indicate the sign of the shock symptoms.